New world record - first pp collisions at 8 TeV

CMS event at 8 TeV showing the effects of "pile-up" (more than one pp collision occuring withing a single crossing of the LHC beams).

Magnified view of the event above showing that 29 distinct vertices have been reconstructed corresponding to 29 distinct collisions within a single crossing of the LHC beam.

CMS has just recorded the first collisions with stable beams at a world-record collision energy of 8 TeV[1].

CMS took good quality data with all sub-detectors working well.

The LHC fill lasted for 1h34min and the "pile-up" at the beginning of the fill was ~27 pp collision events per bunch crossing.

Real collision event inside CMS

A real proton-proton collision event with a centre-of-mass energy of 8 TeV[1], as seen in the CMS detector on 5th April, 2012.

The LHC circulates bunches of protons, each containing hundreds of billions of protons. When the bunches, travelling in opposite directions inside the LHC, cross inside CMS, multiple collisions of pairs of protons occur.

In this event, 23 pairs of protons collide, resulting in the production of a high number of particles.